The science of it is still being worked out, and many of the suggested schemes have proven controversial with conservationists and scientists alike.

Here are five ways scientists can basically terraform Planet Earth to wage war on climate change.

Fertilizing the oceans with iron to nourish phytoplankton

Phytoplankton bloom off the coast of Argentina. Image: NASA

“Give me half a tanker of iron, and I’ll give you the next ice age,” was the boast of oceanographer John Martin back in the late 1980s, when scientists really started studying the effect of iron on the growth of oceanic life like phytoplankton.

The idea is, seeding the oceans with iron or iron-rich substances will spark the growth of single-cell algae, called phytoplankton, which consume CO2 from the oceans and the atmosphere.

Eventually, they’ll die off, and sink into the ocean depths, taking the collected carbon with them and removing it from the atmosphere for decades or centuries.

More research in 2012, however, suggested the method DOES work, but due to concerns of harmful side effects – like toxic algae blooms and depleted oxygen levels – a 2007 convention banned the commercial dumping of iron into the sea for now.

Trouble is, U.S. entrepreneur Russ George either didn’t get the memo, or didn’t care; He teamed up with the Haida nation at Old Masset on B.C.’s Haida Gwaii Islands to dump 100 tonnes of the stuff into the ocean, ostensibly to boost salmon stocks by increasing phytoplankton levels.

Old Masset’s economic development officer claimed a bloom of 10,000 square kilometres attracted large numbers of birds, fish and whales, but no data has emerged just yet, and Environment Canada, who didn’t approve the move, was furious.

Old Masset rejected most of the allegations around the iron dump and, as of earlier this year, was planning another attempt. Still, regardless of the details, the whole incident did little to dissuade opponents of geoengineering.

Dumping aerosols into the atmosphere to produce global dimming

You know things are getting bad when, after decades of trying to reduce air pollution, one of the weapons in the climate change fight involves pumping even MORE particles into the atmosphere.

Image: Gopherboy6956/Wikimedia Commons

Stratospheric sulfuric aerosols involve seeding the atmosphere with small amounts of sulfuric acid, hydrogen sulfide or sulfur dioxide. This would thicken it enough to produce a limited dimming effect, and hopefully reduce global warming.

Like the iron-seeding scheme, this one has roots in already existing natural processes. Some researchers look to the 1991 eruption of Mt. Pinatubo, which dumped so many particles into the sky that it actually increased photosynthesis in one studied deciduous forest by up to 23 per cent the following year. More photosynthesis means more processing by plants of CO2, the key ingredient in global warming.

Image: U.S. Geological Survey Photograph taken by Richard P. Hoblitt.

Scientists are looking at delivery methods for the aerosols, like balloons or artillery rockets, but as the science proceeds, more potential side effects are emerging.

Also, if researchers are using past volcanic eruptions as an example, they can’t ignore the 1815 eruption of Mt. Tambora, which dumped so many aerosols into the atmosphere it caused a global drop in temperature by up to three degrees – causing famine and late season blizzards and frosts.

With the science of it still very young, it’s no surprise that its regarded in some circles as a “last resort.”

Whitening clouds to reflect more sunlight

If the sun’s rays are such a problem for global warming, why not just bounce them back out into space?

One way to do this: Thickening clouds to make them appear whiter, and more reflective, by injecting more salt water into the atmosphere.

Image: NASA/Goddard Space Flight Center/Reto Stöckli

It seems saltwater particles are better at serving as precipitation nuclei. Research suggests whiter clouds can increase our planet’s albedo, or reflectivity, by three per cent can counteract a year’s worth of CO2-caused global warming.

These researchers suggest building a huge fleet of special, unmanned ships – about a thousand of them in total – to roam Earth’s oceans, sucking up salt water and condensing it into the air at a rate of 50 cubic metres per second.

They’d have to do it continuously, as the cloud whitening effect would disappear after only a few days in the event of a shutdown (the upside of that is that, if needed, the whole thing can be shut down on short notice).

Some major figures, like Bill Gates, are getting in on it. The technology magnate poured $300,000 into a pilot project to design the mechanisms you’d need to disperse the saltwater.

Check out this report at around the 0:30 mark:

But his efforts have been criticized by campaigners who say all geoengineering projects should be put on hold until international bodies can work out regulations governing them, not to mention what kind of unintended consequences might ensue.

Aside from the construction and operating costs, though, it would be an enormous amount of effort on what would essentially be a stopgap measure.

The real challenge is bringing global C02 levels, the main cause of global warming, down to more manageable levels, and cloud whitening and other sunlight-reflecting measures would only be buying time.

Planting shinier crops

You needn’t rely solely on whiter clouds to bounce solar radiation back into space. Almost any light-coloured surface will do.

Up to, and including, plants and cash crops, believe it or not.

Image: USDA/Wikimedia Commons

You wouldn’t think of agricultural produce as a reflector of solar energy, but scientists late last decade estimated that, if you plant enough of them, certain varieties of crops, modified or not, can be used to reflect enough sunlight to offset global warming by as much as 1.9C in some estimates.

Waxy coatings and broader leaves count for a lot, and the increase in reflectivity, or albedo, varies from crop to crop.

It’s already been determined that a particular variety of soya bean, bred to be extra hairy and raised in Brazil, reflected five per cent more light.

Barley can reflect a total of 23 per cent of sunlight, while sugar beets raise that to 26 per cent, and it seems higher albedo crops help retain soil moisture, a boon for drought-stricken areas.

Image: Hans Hillewaert/Wikimedia Commons

The concept is still relatively new, and one drawback is that it could take up to 15 years to plant or expand enough such crops to make any kind of difference.

Higher albedo surfaces are becoming more and more prominent in the field of climate change research, with a lot of attention being given to whitening urban surfaces and even house roofs.

Launching countless orbital sunshades to deflect the sun's rays

Image: NASA

If we’re going to talk about drastic measures, you needn’t look further than this concept: Launching countless butterfly-sized solar shields into orbit to scatter and deflect sunlight.

It sounds like science fiction, and connoisseurs of the genre are probably already familiar with the concept.

But one U.K. scientist thinks it can be done…At a cost of $4 trillion, more than twice Canada’s entire present-day gross domestic product.

It gets more outlandish. Stacks of these orbital sunshades would be launched into space, not by rockets, but by Earth-based railguns – at a rate of one load every five minutes for ten straight years.

And the end result? When enough of them are up there, they may be able to reduce total solar radiation by around 1.8 per cent. Doesn’t sound like much, but the theory is that will be enough to reverse the warming effect of a doubling of atmospheric C02.

The multi-trillion-dollar price tag is enough reason to balk though, and just like concepts like cloud whitening and planting high-albedo crops, it wouldn’t address the problem of elevated CO2 levels.

With climate change growing as a focus of public policy, we’ll have to see how the world’s governments decide which geoengineering method, if any, is best to mitigate its effects.